1. Overview The NHLBI Pathology Core Facility provides a full range of histopathological services for the DIR program. Our services include histology tissue procedures, diagnostic histo-pathology evaluation and training for histology and immuno-histo-chemistry procedures. Core Services: 1) The main services of the Pathology Core are histology procedures, such as formalin-fixed tissue embedding, sectioning and histology staining. For this purpose, the Core receives samples in fixed or in fresh condition. These samples are processed and embedded in paraffin or OCT component for either paraffin or frozen sections. The paraffin embedded samples can be cut routinely as 5 micron thick sections mounted on glass slides. The serial sections through an entire organ or embryo, or mixed with thick (20-100 microns) and thin (5-10 microns) step sections also can be cut upon request. Frozen sections are normally cut at a thickness of 8-10 microns. The Pathology core provides routine histology staining with Hematoxylin and Eosin according to the Harris methods (Laboratory Methods in Histotechnology. Armed Forces Institute of Pathology, Edited by Prophet EB, Mills B, Arrington JB and Sobin LH, pp 56, American Registry of Pathology, Washington, DC, 1992). In addition, we also perform special histology staining, including PAS, Masson tri-chrome, Movat, Elastic Van Gieson and Oil-Red O stain. All these services are performed by the Core staff and finished in a timely manner. Most requests are completed within a two-week period, except urgent requests that can be arranged as a higher-priority request. In some cases, results can be returned to users the next day. 2) Diagnostic pathology. For this service, the Core head is involved in discussion of experimental design, sample collection methods and final evaluations of the results. We provide histology products such as cut and stained histology slides, perform immune-staining procedures, evaluate the results, describe the findings and make a scoring sheet with representative photographs. In most cases, this service will contribute to a manuscript submission and we will provide final microscopic figures. 3) Training, consultation and trouble shooting for DIR scientists and fellows in the fields of histo-pathology and immuno-histochemistry. We provide training for tissue processing, embedding and sectioning for paraffin and frozen samples. In addition, we also offer testing for antibodies and for immuno-staining procedures and consultation for immuno-staining problems. 4) Instrument in the Core for users access: a. Currently, our Core has several instruments opened to core users, including a Leica CM3050S cryostat for frozen sections and a Leica DM 4000 B light microscope equipped with digital camera for histology images. b. Our Core installed a new Hamamatsu Digital slide scanner, NanoZoomer 2.0RS on October 7, 2014. This digital scanner can scan entire histology slides with 20x or 40x magnification automatically at high resolution. It can hold 6 slides each time and is suitable for histology analysis, illustration and image archiving. The scanner is located in 10/5N315 and it has been connected to the DIR shared drive for users to transfer lager sized files to their own computer to perform further analysis. 2. Operational analysis Since our last report, the pathology core had total of 285 requests for the services listed above. Core users include 68 fellows/doctors from 31 PIs/ laboratories. We have processed a total of 2,647 tissue blocks and cut 22,989 histology slides, which are usually mounted with 2 or 3 tissue sections. Among them, there were 3,483 slides stained with Hematoxylin and Eosin for routine histology. In addition, we also performed 1,486 slides for other specific staining procedures as mentioned above. Core head is involved in the services for histo-pathological analysis, and immunostaining on research projects for 11 scientists from 6 PI/laboratories including histo-pathological diagnosis, histology evaluations with the score system and provided final images for publications. These resulted in 8 publications in 2014-2015. The Pathology Core offers training for cutting frozen/paraffin sections, immunohistochemistry procedures and histology microphotograph by using Core bright field microscopy equipped digital camera. Core head worked closely with Core Users for selection of antibodies and protocols, and then provided hands-on staining demonstration until the scientist can perform the procedures independently. Currently, we have 20 users for the Leica DMB-4000 microscopy and 8 for the Cryo-stat (Frozen sections). Since the new NanoZoomer scanner was installed, we have 13 users were trained and have used the scanner for 136 hours.